The present invention concerns a process for the preparation of a composition for the dyeing of human hair on the basis of a fine, aqueous emulsion, comprising at least one oxidation dyestuff precursor.
Compositions for the permanent dyeing of human hair on the basis of oxidation dyestuff precursors are wide-spread. In general, their application is carried out by a method wherein a composition, usually in form of an aqueous emulsion, comprising at least one oxidation dyestuff precursor, and generally at least one developing and at least one coupling substance, is mixed shortly before application with a composition comprising a peroxide, the mixture then being applied to the hair.
Preparation of this emulsion is carried out by hot emulsification of the components and subsequent cooling, which naturally takes some time, while not always leading to stable emulsions.